Radioactive Waste Encapsulation and Containment, Oak Ridge, Tennessee, USA

A low pressure permeation grouting program was performed in and around trenches used during the fifties and sixties to discharge high level, liquid radioactive waste. Multiple pass, multiple hole permeation grouting program directed by ECO was implemented via driven, vertical, steel sleeve pipes inside the trenches, using cement based suspension grouts. All sleeve pipes were tested before and after driving to ensure there was no migration of radioactive materials into the sleeve pipes. The grouting was performed with grouts containing besides water and cement, type F fly ash, bentonite, superplasticizer, biopolymer and hydration control agent. Most sleeves were injected 3 or 4 days in a row, causing gradual pressure filtration in the grout to ensure a durable end product with very low permeability. State of the art high production high shear mixers were used, injecting as much as 85 cubic yard of grout per day. The cement grouting operation was followed by the grouting of the heterogeneous soils around and below these trenches with poly-acrylamide grout, using battered sleeve pipes. This multiple hole grouting operation was executed around the clock. Each sleeve received 2 to 5 grout passes. The target residual in-situ hydraulic conductivity value of 1.0x 10-5 cm/s was verified via more than 50 check pipes and successful results were achieved everywhere.